While the 1.0 and 1.2 spin of the bf533-stamp boards can handle the higher
SCLK speeds just fine, the 1.1 spin cannot due to the bugs introduced with
the shortened SDRAM traces.  So lower the SCLK speed down to a value that
all three can handle.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>